In many prior art lamps, the lamps are made glasses. In the manufacturing process of the lamps, the lamps cannot be made with uniform distributed weight so that they are easily to incline to one side. Thereby it is necessary to adjust the lamps in a vertical position. Referring to FIG. 1, it is illustrated that a lead wire 11 is extended from an upper end of the lamp 10. A long sleeve 12 encloses the wire 11. Adjusting the sleeve 12 will make the lamp 20 be in a vertical position. Furthermore, the installation of the sleeve 12 can make a visual effect of causing the viewer to feel the lamp to be in a vertical position. However its effect is not preferred.